Making private MCP servers reachable without making them public | OpenAI Developers

This post introduces Secure MCP Tunnel and Harpoon, which significantly enhance the agentic execution environment by enabling secure, outbound-only connections from private enterprise networks to OpenAI products. This allows agents to access private data and services (via MCP or REST APIs) without requiring public endpoints or broad network access, thereby preserving security boundaries and simplifying integration for developers. It also emphasizes the inspectable, customer-controlled nature of the tunnel client and extends the connectivity model beyond MCP to general REST APIs.